JPS6189282A - Absorbent for temperature controller of absorption type - Google Patents

Abstract

PURPOSE:The titled absorbent suitable as an absorption type heat pump workable by a heat source with a low-temperature difference, having a high pressure gradient, obtained by blending a solution of a chloride monomer with a solution of a compound unreactive with the monomer, having a high water vapor pressure gradient. CONSTITUTION:(A) The first solution containing a chloride monomer is blended with (B) an aqueous solution of a monomer not to be reacted chemically with the solution A, having a larger water vapor pressure gradient than that of the solution A, to give the aimed absorbent. In order to obtain an absorbent having higher absorption properties and a larger water vapor pressure gradient, preferably an aqueous solution of a chloride monomer such as calcium chloride, etc. is mixed with an aqueous solution of magnesium chloride, etc. to raise absorption properties, and then mixed with an aqueous solution of lithium chloride, etc. having a larger pressure gradient.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an absorbent used in an absorption heat pump or an absorption refrigerator using an aqueous solution, and is particularly suitable for operation using a heat source with a lower temperature difference. This invention relates to mixed absorbents for absorption heat pumps and absorption refrigerators.

[Background of the invention]

Until now, most of the absorbents used in absorption refrigerators and heat pumps have been lithium bromide aqueous solutions. Until now, high-temperature heat sources such as gas or heavy oil combustion gas have been used as the operating heat source to separate water from a lithium bromide aqueous solution as steam. There was a need for something that had a higher solubility, could be obtained from a higher concentration aqueous solution, had greater absorbency (lower water vapor partial pressure), and was less susceptible to corrosion at high temperatures. However, in recent years, separation of absorbent and water has been developed.

Relatively low temperature heat sources such as solar heat and waste heat have come to be used as operating heat sources. When a heat source with such a low temperature is used, the above-mentioned moisture separation cannot be performed sufficiently, so the temperature does not drop sufficiently in an absorption chiller, and conversely, the temperature does not rise sufficiently in an absorption heat pump. have. Therefore, in recent years, due to oil resources, it has become necessary to develop absorbents suitable for absorption heat pumps and absorption chillers that operate on low-temperature heat sources such as solar heat. If we consider comprehensively the properties of the absorbent used in absorption heat pumps and absorption refrigeration systems that can operate with low-temperature heat sources, K will improve the performance of the system without complicating it compared to conventional systems. Basically, the following two methods can be considered.

The first method is to optimize the absorbent used in current absorption refrigeration systems as shown in FIG. The refrigeration system shown in FIG. 5 includes a concentrator 100 that evaporates water in the absorbent 10, which is an aqueous solution, to concentrate the absorbent 10, and a condenser 100 that evaporates the water condensed in the concentrator at a low temperature and absorbs it into the absorbent 10. diluter 200 for diluting the absorbent 10
When the absorbent diluted by the diluter 200 is forcibly returned to the concentrator 100 using a pump or the like, the concentrator 10
It is composed of a heat exchanger 300 that gives heat from the concentrated liquid sent to the diluter 200 from 0 to the diluted liquid. This concentrator 100 is comprised of a regenerator 110 that evaporates water from the absorbent 10 and a condenser 120 that condenses generated water vapor 20. As the heat source of this regenerator 110, hot water from a solar water heater or hot water using waste heat is used in the pipe line 115.

Further, the condenser 120 is provided with a pipe line 125, and the cold water flowing through the pipe line 125 is used to feed the regenerator 11.
The water vapor sent from 0 is cooled and condenses. In addition, water 30 is condensed and sent into the diluter 200 tl condenser 120.
The absorber 220 absorbs the water vapor 21 generated by the evaporator 210 into the absorbent 10 of the concentrated solution.

This evaporator 210 is provided with a pipe line 215.

This conduit 215 is configured to allow water to flow therein. The inside of this evaporator 210 is kept at a lower pressure than the inside of the condenser 120. Therefore, water 30Fi sent from the condenser 120 becomes water vapor when it enters the evaporator 210.
On the other hand, the absorbent 1G from which water has been separated in the concentrator 100 is taken into the absorber 220 as a concentrated liquid. Since the concentrated liquid taken into the absorber 220 is soluble, it absorbs the water vapor 21 generated in the evaporator 210. By absorbing this water vapor 21, the pressure inside the evaporator 210 is reduced, and the steam of the rice 3o is further promoted. In this evaporator 210, the water in the pipe line 215 is cooled by the heat of vaporization when the water 30 is evaporated.

Further, inside the absorber 220, the concentrated absorbent absorbs water vapor, and the temperature rises due to this absorption reaction.

Therefore, in order to increase the absorption efficiency, a pipe 225 is provided inside the absorber 220, and water is passed through the pipe 225 to cool the inside of the absorber 220.

Further, the absorbent 10 that has become diluted by absorbing water vapor in the absorber 220 is sent to the regenerator 110 via a pipe line.

It is configured to pass through a heat exchanger 300 before being sent to the regenerator 110. This heat exchanger 300 is the regenerator 1
Since it is heated to evaporate water in step 10,
The concentrated absorbent also has a higher temperature. A heat exchanger 300 is provided to transfer this temperature to the diluted absorbent 10 which is fed to the regenerator 110. This heat exchanger 30G heats the diluted absorbent returned from the absorber 220 to the regenerator 110, and at the same time heats the diluted absorbent from the regenerator 110 to the absorber 22.
Sent to 0. It has the effect of adding concentrated absorbent. This increases the water vapor absorption efficiency of the absorbent.

Next, the operation of the refrigeration system shown in FIG. 5 will be explained using FIG. 6.

In this absorption refrigeration system, first, the diluted absorbent is at a pressure of P! Regenerator 11 in condenser 100 maintained at
At G, the pipe 115 is heated to a temperature T3 by hot water at a temperature T4 supplied from a solar water heater or the like. This heating evaporates the water in the diluted absorbent, and the water vapor 20 is sent to the condenser 120, where the absorbent 10 is concentrated. This water vapor 20 is cooled and condensed at a temperature T by cooling water sent into a conduit 125 in a condenser 120 . This condenser 1
The water 30 separated at 20 enters the evaporator 210 in the diluter 200 at a pressure P1. This evaporator 21
0, the pressure is Pl, so the water at temperature T is 30
is evaporated, and by removing the heat of vaporization during this evaporation, the temperature inside the evaporator 210 is lowered to a temperature TI. The water vapor 21 generated in the evaporator 210 is absorbed by the concentrated absorbent 10 in the absorber 220.

Since heat is generated during this water vapor absorption, the temperature inside the absorber 220 becomes T1. In other words, in the absorption refrigeration system, a solar ring O heat source at temperature T4 is added to the regenerator 110 via the pipe 115, and industrial water, air, etc. are sent from the pipe 125 to cool the condenser 12G, and the pipe 225 to cool the feed absorber 220 and remove heat. By doing so, cold heat at a temperature T1 is obtained from the evaporator 21G by water flowing through the pipe 215. Here, regenerator 1
The temperature T4 of the heat source sent to the evaporator 10 via the pipe 115 and the temperature T of the cooling water sent via the pipe 125 to cool the evaporator 21()! In order to obtain a lower temperature T1 using a relatively low heat source with a small difference (T4 - Tz) from 0 to θ'
It can be obtained by That is, the degree to which the temperature inside the evaporator 210 can be lowered is determined by how far the pressure is reduced by the absorbent 10 evaporating and absorbing water at the temperature T3. That is, the pressure gradient is 0.
If we can obtain an absorbent with a large temperature difference, we can obtain a lower temperature than before even if we use the same system as the current system and a heat source with a low temperature difference. As explained above regarding the absorption refrigeration system, in the absorption heat pump system, the heat generated during absorption of water vapor is used for heating, so the pressure gradient 0 of the absorbent used should be as small as possible to obtain a higher temperature T3. You will be able to do that.

The second method uses two types of absorbents to increase efficiency □
The basic system is shown in FIG. 7, and the operating diagram of the system shown in FIG. 7 is shown in FIG. This system shown in Fig. 7 is the fifth
The difference from the illustrated system is that in addition to the circulation loop of the absorbent 10, the loop through which water 30 has flowed up to now is now the circulation loop of the absorbent B15. That is, the condenser 120 in the system shown in FIG.
0 to regenerator 8230, heat exchanger 3 of absorbent B15
10 has been added. A method for improving the performance of the absorption heat pump system will be described below with reference to the illustrated operating diagram in FIG. In a heat pump, the smaller the pressure gradient of the absorbent used, the higher the temperature can be obtained. Generally speaking, the higher the concentration of an aqueous solution, the smaller the pressure gradient 0, so it is effective to increase the concentration.

Further, the higher the absorption pressure P1 of the absorbent, the higher the temperature can be obtained. Therefore, the second absorbent B is introduced taking both of these into consideration. In other words, the water vapor generated in the regenerator 110 of the concentrator 10G is not condensed as in the system shown in FIG. 5, but is absorbed by the absorbent B15 in the absorber B130 to lower the concentration pressure from P to P2'.
While making it possible to concentrate the absorbent 10 to a higher concentration,
By increasing the pressure gradient 0# of absorbent B15,
The pressure P1' of the diluter 200 is increased by P*'K to obtain a higher temperature Ill,t. Absorbents with large pressure gradients also play a major role in this method.

From the above, in addition to the current absorbent such as lithium bromide aqueous solution, the introduction of a second absorbent with a larger pressure gradient is the key to developing absorption heat pumps and refrigerators that can operate at low temperature differences. .

In addition, as something related to the present invention, a hydrogen absorbent tc
) Iteha, cold 1j [VoA52-No 600Kt, 3-component system (H2O-LiBr-LiC1, etc.) IIC) E-C, frozen VoA44-N 050
2'', but the vapor pressure gradient is not mentioned at all, and the development of absorbents focuses solely on increasing absorbency (that is, increasing solubility).

[Purpose of the invention]

An object of the present invention is to provide a mixed absorbent with a large pressure gradient that is suitable for absorption heat pumps and refrigerators that can be operated using heat sources with low temperature differences.

[Summary of the invention]

After the inventors invented a new system using the two types of absorbents shown in Figure 7 (!II 1975-32757), they investigated and studied various absorbents suitable for the system, but the currently used aqueous solutions However, no large pressure gradient was found. Therefore, we selected several types of chlorides as hygroscopic, highly soluble, and safe aqueous solutions, and developed an absorbent that could change the solubility and pressure gradient by mixing them. .

The idea of the present invention is based on the following phenomenon. ■ Single-component chlorides have some pressure gradient depending on the type, but their solubility in water is low, which means that high temperatures cannot be obtained; ■ Generally, as the concentration of chloride increases, the pressure gradient decreases, but , The extent of this change differs depending on the chloride, ■ The apparent solubility improves somewhat when chlorides are mixed, and ■ The pressure gradient also changes when chlorides are mixed, but there is a limit to the mixing ratio.

The basic concept of the present invention is (1) to select a highly soluble chloride such as calcium chloride in order to increase the concentration, and at the same time, if necessary, mix multiple chlorides to increase the apparent salt concentration;

Next, (1) In order to increase the pressure gradient, a chloride which has low solubility when used alone but has a large pressure gradient, such as lithium chloride, is mixed at a mixing ratio of 204 or less of the total mixed aqueous solution concentration. By the above operations, a mixed absorbent having a relatively high concentration and a large pressure gradient can be obtained.

[Embodiments of the invention]

Examples of the present invention will be described below.

In the examples, when selecting the target aqueous solution, chloride and bromide are selected as hygroscopic, highly soluble, and neutral substances, and both are sufficient to be covered by the present invention, but there are safety concerns. Chloride was selected based on this point. Next, select chloride, lithium, calcium chloride, etc. as those with high solubility and large pressure gradient among chlorides,
Magnesium chloride and zinc chloride were selected for the purpose of increasing solubility.

[Example 1] Figure 1 shows changes in water vapor pressure characteristics obtained from an experiment in which calcium chloride was added to a 35-W aqueous solution of lithium chloride, which is excellent in solubility and high pressure gradient. the result,
By adding calcium chloride, the water vapor absorbability increases (the water vapor pressure of the mixed aqueous solution decreases), and the pressure gradient also tends to increase somewhat. From this result, it was found that the change in absorbency and pressure gradient with respect to the amount of calcium chloride added was
As shown in the figure. In this ζ, the absorbency is water vapor pressure 10KPa
The pressure gradient is indicated by the gradient ΔP/ΔT in the diagram shown in FIG. As a result, as calcium chloride is added to lithium chloride, the absorbable TIO increases proportionally as shown in Figure 2 for humans, but the pressure gradient increases greatly during addition; It can be seen that the rate of increase becomes smaller, and conversely decreases when it exceeds the line 0-) shown in FIG.

In this way, the absorbency increases as other substances are added, but it has become clear that there is an addition limit (addition rate of 20-) for increasing the pressure gradient. This tendency is similar to when a small amount of lithium chloride is added to calcium chloride, as shown in Figure 2B, and since the pressure gradient of calcium chloride alone is large, the pressure gradient obtained by adding lithium chloride to it is greater. is larger than when calcium chloride is added.

Based on the above, in order to create a mixed absorbent with higher absorbency and a larger pressure gradient, first add calcium chloride, magnesium chloride, which has a high pressure gradient to increase the absorption, and then add a small amount of lithium chloride. This can be done by

[Example 2] Based on the above Example IK, magnesium chloride was added to an aqueous solution of calcium chloride of 301 to increase the absorbable TIO to a total concentration of 411, and then a small amount of lithium chloride was added. The relationship between the amount of lithium chloride added and the pressure gradient is shown in FIG.

This figure 3 shows that when a small amount of lithium chloride is added to a mixed aqueous solution of calcium chloride and magnesium chloride (addition rate of 1611), the pressure gradient increases, but if it exceeds that amount, it tends to decrease. .

From the results of Examples 1 and 2, it was found that other chlorides, such as lithium chloride, which alone have a large pressure gradient, were added to a simple aqueous solution of calcium chloride, etc., or a mixed aqueous solution of it and another substance, such as magnesium chloride. If it is added at a rate of 20 - or less, the pressure gradient can be increased. Further, the pressure gradient can be increased by adding another chloride having a large pressure gradient, such as calcium chloride, to an aqueous solution of lithium chloride alone or a mixed solution of lithium chloride with another substance at an addition rate of 20 or less.

[Example 3] Figure 4 shows the water vapor pressure characteristics of the mixed absorbent prepared based on the example. The mixing ratio of calcium chloride, magnesium chloride and lithium chloride exhibiting the characteristics shown in Figure 4 is 11.
:3:1 and the addition rate of lithium chloride to the total concentration is 79 g, but compared to the lithium bromide aqueous solution of 55-
The pressure gradient is quite large.

[Effects of the present invention]

As explained above, according to the present invention, there is absorbency,
In addition, it is possible to provide an absorbent with a large pressure gradient, and by using it in absorption refrigerators and absorption heat pumps, it is possible to obtain colder heat at a lower temperature or heat at a higher temperature by using a heat source with a lower temperature difference. There is an effect that can be done.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram of an absorbent showing an embodiment of the present invention, Fig. 2 is a characteristic diagram of an absorbent showing another embodiment of the present invention, and Fig. 3 is a characteristic diagram of an absorbent showing another embodiment of the present invention. Fig. 4 is a characteristic diagram of the specific mixing ratio of the absorbent based on the illustrated embodiment in Fig. 3, and Fig. 5 is a diagram of an absorption refrigeration system using the mixed absorbent according to the present invention. Fig. 6 is an operating diagram of the system shown in Fig. 5, Fig. 7 is a diagram of an absorption heat pump system using two types of absorbent using the mixed absorbent of the present invention in the middle, and Fig. 8 is a diagram of the system shown in Fig. 7. It is a system diagram. 100... Concentrator, 200... Diluter, 10.
...Absorbent, 30...Water, 15...Absorbent B Fig. 1, a Hama T (@C) Fig. 2 Total 4 columns C (%W) Fig. 3 Fig. 4 Fig. 1 Skin T ( @C) Figure 5 Figure 6; z*r -m- Figure 7vjA Figure 8

Claims (2)

[Claims] (1) By a first solution composed of a simple chloride and a mixture of one or more kinds that do not cause a chemical reaction with the first solution and have a larger water vapor pressure gradient than the first solution. An absorbent for an absorption type temperature conditioner, characterized in that it is constituted by a mixture with a second solution. (2) a first solution composed of a single chloride; a second solution composed of one or more mixtures having better water vapor absorption than the first solution;
and a third solution that does not cause a chemical reaction with the second solution and is composed of a mixture of one or more types of water vapor pressure gradient that is larger than that of the first solution. An absorbent for absorption type temperature conditioners featuring the following.